1. Field of the Invention
The present invention relates to a signal encoding apparatus for encoding an audio signal or audio and video signals to audio data or audio/video data to be recorded in an audio recording medium, an audio data transmitting method for transmitting the audio data encoded in the encoding apparatus through a transmission medium, an audio data recording method for recording the audio data transmitted according to the audio data transmitting method in the audio disc, audio data decoding method for decoding the audio data transmitted according to the audio data transmitting method, and an audio disc for recording audio data to be read out from its top position.
2. Description of the Related Art
2.1. Previously Proposed Art
A conventional compact disc (CD) has been known as a conventional audio signal playback optical disc. Also, a digital video disc (or a digital versatile disc) (DVD) has been recently known as an optical disc having a packing density higher than that of the CD. The digital video disc is called DVD-video disc in this specification.
Also, a DVD-Audio disc has been recently known as an optical disc for music.
2.2. Problems to be Solved by the Invention
However, in cases where both a video signal (or video data) and an audio signal (or audio data) are recorded in the same DVD-video disc, the video signal is primarily recorded in the DVD-video disc, and the recording of the audio signal is subordinated to the recording of the video signal. Therefore, there are following problems.
First, the audio signal is integrated with the video signal in the DVD-video disc, so that the audio signal and the video signal are recorded as a set. Therefore, a memory capacity for the audio signal is considerably lower than that for the video signal.
Secondly, a time management for the audio signal cannot be performed independent of the video signal.
Thirdly, simple text information such as a music name cannot be read out from the DVD-video disc.
Also, because users, who are entertained with music obtained by playing back the audio signal, desire the DVD-video disc to be used for various purposes as compared with users entertained with a picture relating to the video signal, a simple audio play method is required of the DVD-video disc. For example, the users for the audio signal desires to arrange an area of table-of-contents (TOC) in the DVD-video disc in the same manner as in the CD. However, in the DVD-video disc, a video contents block unit is composed of a navigation control pack (called a CONT pack), a plurality of video (V) packs and a plurality of audio (A) packs, and the playback of the video and audio packs is controlled by using the CONT pack. Therefore, even though a user intends to primarily record the audio signal in the DVD-video disc independence of the video signal, a user cannot easily play back the audio signal, so that there is a problem that the DVD-video disc is not very useful for the user.
Also, the time management in the DVD-video disc is performed for each video frame. Therefore, even though a user intends to primarily record the audio signal in the DVD-video disc independence of the video signal, because it is important to continuously play back the audio signal as compared with the video signal, there is a problem that it is difficult to perform a time management for the audio signal in real time.
Also, in cases where a musical composition is recorded in a DVD-Audio disc, when the musical composition is played back, users desire that the musical composition is easily played back from its top position. Also, it is convenient for users that the DVD-Audio disc is compatible with the DVD-video disc.